The present invention relates generally to a hydraulic jack apparatus and more particularly to a hydraulic apparatus for raising and lowering an impeller shaft to facilitate servicing of the impeller.
In the use of large impellers, it is periodically necessary to make various service adjustments to the impeller apparatus which necessitates raising, and in some instances subsequently lowering, the impeller shaft. For example, it is necessary to periodically change a cartridge seal assembly in many impeller apparatuses. An another example, in surface aerators it is sometimes necessary to adjust the vertical location of the impeller. These operations may necessitate raising the impeller shaft a distance on the order of six inches to a foot or more. In large impeller apparatuses the impeller shaft may weigh several thousand pounds. Accordingly, some type of lifting assembly must be employed to lift the impeller shaft.
In the past, more frequently, a screw type lifting apparatus has been employed to lift the impeller shaft. Although such screw type assemblies have generally functioned in an acceptable manner, they have exhibited some shortcomings. These screw type assemblies require the use of a ball bearing member which must carry the entire load. These ball bearing members present a rather severe limitation on the lifting capabilities of the screw type lifting assemblies. Additionally, such screw type assemblies require a significant amount of manual effort to operate the assembly and also require additional head room above the lifting assembly to allow room for retracting the screw. In some instances, on extremely large impeller apparatuses permanent hydraulic lifting assemblies have been utilized. However, to date, no hydraulic lifting apparatus has been developed which may be easily mounted atop an impeller apparatus for raising and lowering the impeller shaft.